Up the Creek With Two Robot Paddles

Sometimes the stresses of life start to pile up and we feel the need to get away from it all for a while. Everyone has their own way to unwind, but for Dave Niewinski the ideal way to relax is to hop on a canoe and float down a quiet river. Niewinski doesn’t find the whole part about paddling to be quite so relaxing, however. A motor would make things easier, but at the expense of adding noise to an otherwise serene experience. What is a stressed out robotics engineer to do?

Get robots to do the unpleasant work, of course! Niewinski came up with a plan to get a pair of robotic arms to do the paddling for him. He already had a pair of 6-DoF PiPER arms made by Agilex Robotics that should do the job, and he was able to borrow a canoe from a friend, so most of the hardware was already good to go. He would just need a way to mount it.

The mounting solution would have to be very light, because the robot arms were only just barely powerful enough for paddling. It would also have to work without modifying the boat, as it was borrowed. The solution Niewinski developed was composed of aluminum extrusions anchored by pressure-fit braces that ran from one side of the canoe to the other. The PiPER arms were mounted to the rails on either side of the boat.

To control the arms, an NVIDIA Jetson Orin Nano was chosen. It has plenty of power, yet it is not especially expensive, so in the worst case, Niewinski wouldn’t be out too much cash. The Jetson runs a ROS-based control algorithm that treats the arms as wheels using a differential drive approach. A video game controller supplies inputs, which are converted into speeds for the “wheels.” These speeds are fed into a hardware interface that calculates where each paddle is in its stroke, then uses inverse kinematics to determine how each paddle should move. The calculated joint angles are sent to each arm.

You can’t exactly plug a canoe into an electrical output, so a BLUETTI AC200L Power Station was brought onboard the boat. It can supply 2kW of energy through both AC and DC outputs. That is enough to keep the canoe chugging along for a long journey, and it can be recharged via solar power if Niewinski accidentally ventures too far.

The boat was tested out in a local river, and it appeared to work quite well. It was not especially fast, but that was expected because the chosen robot arms are a bit underpowered for the task. That doesn’t really matter, however, because this isn’t a speedboat, this is all about relaxation.

This is a more complex and expensive build than many that we see, so you might not be able to reproduce it yourself. Fortunately, you can live vicariously through Niewinski by watching the video below.